Which is true about Java interfaces?

• A. They cannot have default methods
• B. They can contain static methods
• C. They require a constructor
• D. They are instantiated directly

Answer: (B)

Java interfaces can indeed contain static methods. This feature was introduced in Java 8 and allows interfaces to have static methods that can be called independently of any object instances. Static methods in interfaces can only access static fields or call other static methods defined within the interface but cannot access instance variables or instance methods. This capability enhances the organization of code by allowing related functionality to be grouped together within the interface itself and promotes cleaner code by providing default behaviors.

The other options are incorrect primarily because:

• Interfaces can have default methods, which allow them to provide method implementations while still remaining abstract and promoting flexibility when implementing classes.

• An interface does not require a constructor because it cannot be instantiated on its own. Instead, it serves as a blueprint for classes that implement the interface.

• Interfaces themselves cannot be instantiated directly. They act as contracts for classes to implement, meaning that a class must be created to utilize the interface's defined methods.